Cats. (was yes, yes, YES! )
The previous poster obviously isn't a sys admin, much less a BOFH.
The horses here are great, but being herbivores they hang out in herds, graze and drink water. They also let us ride 'em, after a training period that is pretty much ongoing. Some go to shows (mostly hunter/jumper & dressage, but we have a few western & driving critters too). They need to be told what to do, even micromanaged, pretty much all the time. They live in fields, paddocks, and in the barns at night. They poop & pee when needed, without a by-your-leave. Most have learned that pooping & peeing in the isles of the barns, cross-ties & wash racks is a no-no. Thats about it for horses.
The whippets hang out in their own pack, and with us. They snap the necks of ground squirrels, rabbits, moles, gophers and what have you (as available), eat dog food, drink water. A couple do conformation, most do obedience, some are partial to agility, all chase lures (and ground squirrels). Most understand their "sport" after a little encouragement, and require little re-training or ongoing training. They need to be on-lead when not in a fenced area, as they have no traffic sense and a high prey drive. They live in the house, and sleep most of time. They have a dog door, and poop & pee in the correct corner of their yard. That's about it for whippets.
Cats ... Ah, the cats ... They sometimes allow us to hang out with them. They are loners. They eat anything smaller than them that moves (a few of the larger ones have been caught eyeballing the smaller whippets ...), although we do make certain they have quality chow when hunting isn't as good as it should be. They do what they want, when they want, and we don't worry about 'em (they do get proper vet care). They live all over the ranch, most are feral, all are spayed & neutered (except one old Tom that I haven't managed to trap ... I suspect he's the father of most of our local kittens ...) ... They stay out from under the wheels of the tractors, the water truck, and the yuppies who pay us rent for stall space. A few use the dog doors, and are welcome inside. The whippets all know "cats are sharp" and ignore cats. Most allow us to pet them, occasionally. Most of the horses are afraid of cats ...
Cats won't soil their own nest. Our 240 acres belong to the cats. They share with the folks east, west, and south of us (all of whom understand cats). The cats pee and poop at the outer corners of the ranch, where it won't get in anbody's way ... and in the fancy rose garden/pool area of the asshole who lives just north of us. He hates cats, and they carefully return the favo(u)r ...
The idiot to the north is clueless. And has a serious rodent problem ...
Cats are the ultimate BOFH. We do it their way, and we survive.